Shockwaves and thermal energy created by a dying star

I was wondering yesterday, the shockwaves and thermal energy created by a dying star as it contracts (if that star is big enough) can create an explosion know as a supernova. so, after the supernova exploded, the star will continue to contract and create shockwaves and thermal energy, since these two situations are so much alike, it seems to me like it is possible for a second supernova to occur after the first, but that not true... why?? please tell me =D thanks a lot

I believe your brief research mislead you to think that a supernova continues to contract after it's explosion.
The explosion is caused by a release of contracted energy, hence only one. I would also reason to believe that a supernova could not be possible at a constant point of contraction because that system would resemble a black hole.

I was wondering yesterday, the shockwaves and thermal energy created by a dying star as it contracts (if that star is big enough) can create an explosion know as a supernova. so, after the supernova exploded, the star will continue to contract and create shockwaves and thermal energy, since these two situations are so much alike, it seems to me like it is possible for a second supernova to occur after the first, but that not true... why?? please tell me =D thanks a lot

Here's the basic scenario. The weight of the outer layers of the star is supported by the fusion happening at its interior. If the star is large enough, this process will eventually produce Iron at the core. Iron will not fuse without a net input of energy, so a dead iron core begins to form. When this core gets massive enough, its own atomic collapses under it own weight and it contracts suddenly. This leaves a hollow behind which the upper layers of the Star fall into causing the Sun to suddenly collapse itself. This sudden collapse is enough to cause much of the remaining mass of the star to undergo fusion in one big explosion. Any remaining outer layers are blown away.

Afterward, you are left with the core remnant, and a bunch of material flying away from it. Even if the core where to continue to collapse, it has no fuel left to power another fusion explosion.